Find ANY poem about feet and/or shoes, and underneath that just write: "Please take off your shoes before entering." Next to a selection of socks and slippers, if you want to be the Host(ess) with the Most(ess).

This one comes to mind:

[But] four young oysters hurried up,
All eager for the treat:
Their coats were brushed, their faces washed,
Their shoes were clean and neat --
And this was odd, because, you know,
They hadn't any feet.